An old result of Camina and Herzog states that a finite group G has abelian Sylow 2-subgroups, provided |G : CG(x)| is odd for any 2-element x ∈ G. In my talk, I will report about a generalization of this theorem to saturated fusion systems, which was conjectured by Kühlshammer, Navarro, Sambale and Tiep. This does not only lead to a significant simplification of the proof of the theorem of Camina and Herzog, but also implies a new result in block theory. In my talk I will explain the proof of the main result and give an introduction to the theory of fusion systems along the way.